FOOD OF PLANTS JN GENERAL. 477 



forward the same as its basis, and especially all theories which set forth 

 organic materials as a principal source of nourishment for plants. 



Although the leading propositions, through the above development, 

 may appear to be perfectly firmly established, yet we ought not to dis- 

 dain any individual fact that would confirm or extend their basis. To 

 this end the observation of smaller parts of the earth's surface may 

 serve, which we may in some measure regard as a separated whole. 



The Pampas* of Buenos Ayres, at the time of its discovery by the 

 Spaniards, exhibited the same character as it does at the present day. 

 Endless plains, with mostly a poor though, in the low-ground, a cheer- 

 ful growth of grass, interrupted by paths, and here and there hedged in 

 with strips of Algarobias and Acacias, present themselves, and besides the 

 grave Bizcacho, the Turuturu, and similar small animals, are seen Os- 

 triches, herds of Guanacos, and a scarce population of men. All these 

 remain ; but the Spaniards brought with them between 1530 and 1532 

 horses and horned cattle, which, getting wild, have increased in such 

 immense numbers, that during the war of General Rosas with the 

 Indians 20,000 horses were often lost in a few days. They wander 

 about in countless herds, numbering about 15,000 in each, so that horses 

 and cattle have but little value. The European has extended himself 

 over these districts, and has introduced in the neighbourhood of the 

 great cities a more luxurious vegetation, and the artichoke and the 

 thistle occupy large portions of land. The organic substance in these 

 regions, so far from decreasing, has apparently greatly increased. At 

 the same time, the land, without receiving any remarkable contribution 

 of organic matter since that time, has yielded, in constantly increasing 

 proportions, immense quantities of organic substances.f The hides alone 

 would represent an annual loss of 60,000,000 Ibs. of organic substance. 

 But this is only an inconsiderable part. According to their products, these 

 herds cannot be estimated at much less than 20,000,000, and in a single 

 year they would destroy by the process of nutrition 80,000,000,000 Ibs. 

 of organic matter, or in 100 years 8,000,000,000,000 Ibs. All this 

 organic substance must come from plants ; and who could advocate the 

 senseless position, that all these substances were once humus, or some 

 other organic matter stuck in the barren soil of the Pampas? 



A great part of Central Russia is covered with a soil, which, on 

 account of its colour, is called by the Russians Tschornoisem, black earth, 

 and is distinguished for its extraordinary fruitfulness. The rural 

 economy in this district is about the roughest in the world ; manuring 

 is never once thought of; and those crops alone are sown which momen- 

 tarily promise the greatest return for the least amount of labour. 

 Berzelius has given an analysis of this soil by Herrmann, according to 

 whom a more useful soil does not exist : 



Crenic acid ~| 



Apocrenic acid > combined with iron and alumina = 5-66 per cent. 



Humic acid J 



Humus extract ......= 3*10 



Humin and roots ......= 1*66 



10-42 



* Darwin, op. cit., and Tschichatschew's Rcisen dureh die Pampas. 



f According to M'Culloch, in a period of five years, from 1838 to 1842, Monte 

 Video and Buenos Ayres yielded annually about 90,000,000 Ibs. of oxen and horses' 

 hides, 9,500,000 Ibs. of horsehair, a,nd 3,250,000 Ibs. of ox horns. 



